BENDING SQUARE TUBE/PIPE

square tubing roller machine

Bends often require achieving a tight radius. Since the outer wall of Depending on the outside dimensions, wall thickness, and radius, square tube (square tube) can be rolled or bent in countless ways.

square tube bending machine
square pipe bending machine

SHS Steel / SQUARE TUBE

Square hollow sections/SHS steel ( square tube/pipe ) are another popular type of structural steel tube. They are a kind of intermediate between RHS steel tubing and CHS beams in terms of appearance and structural behaviour. Square section steel also has a flat surface and clean lines — which both make welding and joining very economical.

Square & rectangular tube/pipe bending processes

Six parameters of bending square pipe

The basics of bending are the same for all material in that certain information is required to produce an accurate part of square pipe:

Degree of bend
Radius of the bent section
Chord of the bent section
Arc length
Slope of the bent section
Tangent lengths

It isn’t necessary to know all six parameters. However, at least three must be known to produce a bent section.

Hot Bending VS Cold Bending

In practice, there are many different square & rectangular tube bending processes. In the project, it is usually divided into cold bending and hot bending according to whether the bending is heated or not.

The cold bending method is used to bend the square & rectangular tube at room temperature. Because there is no heating during bending, it is more suitable for bending iron tube, stainless steel tube, aluminum tube and copper tube.

5 square & rectangular tube/pipe bending processes

Square tube/square pipe bending techniques, including:

  1. Rotary draw bending
  2. Induction bending
  3. Roll bending (Can even be bent in plate roller)
  4. Increment bending
  5. Compression bending

Compared with hot bending, the cold bending of automatic square & rectangular tube bender needs more bending power, and the spring back and residual stress increase obviously. The full-automatic square & rectangular bending machine cannot bend sharp bends with small radius of curvature. Hot bending can form small radius elbow on the pipe. For carbon steel pipe and most alloy steel pipe, the bending radius of hot bending is much smaller than that of cold bending by automatic pipe bender, and the bending radius can be as small as 0.7-1.5 times of the outer diameter of the pipe. However, hot bending still has the following disadvantages: complex equipment, high processing cost, low production efficiency and poor surface finish.

four Factors That Influence the Square Pipe/Tube Bending Process

Several tips can help to ease bending square or rectangular material and reduce the amount of distortion in bent sections.

  1. Wall Thickness. Bending round, square, or rectangular material involves stretching the outside diameter (OD) of the bend and compressing its ID. Consequently, a heavier wall thickness allows for a tighter bend radius and more material stretchability with less distortion.
    Method of Bending. This is a key factor in controlling distortion. A correctly chosen procedure can help to produce consistent tolerances and accurate parts. Generally, smaller material requires rotary draw bending or compression bending, which can incorporate wiper dies and mandrels. Induction and increment bending should be used with larger material bent to a larger radius. Design distortion and material size are important factors for determining the bending method.
    In many cases, there is no better factor than experience. Many trained bending artisans know what is required to produce an acceptable product.
  2. Size of Material. Larger material bent to a smaller radius has a greater chance to distort than smaller material bent to a larger radius. Design and planning are necessary to help solve bending problems before they arise.
  3. Tooling. After the parts have been designed, the method of bending has been chosen, and procedures to bend to proper tolerances are established, the machine must be set up with the proper tooling. Based on design conditions, tooling that can be used includes bend die, clamp block, follower block, mandrel, and wiper die. All or some of this tooling may be required.
  4. Internal and External Lubricant. Lubricants decrease the friction between tooling and material to be bent. When friction is reduced, material flows smoothly through the bending equipment, allowing the machinery to perform its designed operation efficiently.

:: Reference: Bending square and rectangular tubing

Selection table of BIT sqaren pipe bending machine for bending square tubes

  Specification (mm) Minimum Inside Diameter (mm)
PBH-120 65 × 6 1000
PBH-140 90 × 5 1500
PBH-200 100 × 6 2000
PBH-300 120 × 8 3000
PBH-360 150 × 8 5000
PBH-450 180 × 10 6000
PBH-500 200 × 10 8000
PBH-550 250 × 12 10000
PBH-600 300 × 12 15000
PBH-700 350 × 12 30000

Tips For Bending Steel Tubes:

Bending Square Tube
bending square tube (square pipe)

However, there is some troubleshooting to do when performing steel tube bending.

Bends often require achieving a tight radius. Since the outer wall of the bend becomes thinner, the result may be a distorted bend. To prevent this, using a mandrel to give support is recommended. That is also why press or ram bending is not recommended in these situations. The most adequate bending method would be mandrel bending, which is the same as rotary draw bending, but adding a mandrel to support the inside of the pipe.

Sometimes the radius we need to achieve makes the steel to exceed its elastic limits. It can result in deformation in the form of a hump or wrinkles. To prevent the formation of humps and wrinkles, it is recommended to use rotary draw bending or three roll bending.

When bending stainless steel tubes and pipes, it is important to remember that some of the stainless steels require around 50% more power for bending than carbon steels. Therefore, that the machinery must be set accordingly.

Bending Profiles Square Hollow Section

BIT series profile bending machine ability to bend both square and rectangular tubing. For rectangular tubing we can bend both the easy way (against the weak axis) and the hard way (against the strong axis). Its can even provide Multi-Plane bending where we are bending both the easy way and the hard way.

Related Reading: Square and rectangular tubing is also known as HSS (hollow structural steel).

Bending Steel & Aluminium Tubes

Section bending machine can bend all types of pipe and tubing including aluminum, stainless and carbon steel. It even bend specialty materials such as copper, zirconium and titanium.

Square and rectangular tubing is always called out the same way. The first two numbers designate the size of the material (in inches). The last number (typically represented as a decimal) defines the thickness of the tubing. An example callout for standard rectangular tubing would be TS 8” x 6” x .375”. This tubing measures 8” long x 6” wide and has a wall thickness of 3/8”. You know this is rectangular tubing because the sides are not equal.

Related Reading:Similarities Between Bending Round and Rectangular Tubing

Carbon square and rectangular materials (mill produced) are classified as ASTM A500 resulting in a yield point (psi) of 39,000 minimum for Grade A and 46,000 minimum for Grade B.

Application

Square and Rectangular materials can be used in virtually any application. Structural (roof trusses), ornamental (staircases), recreational (bike racks), manufacturing (various widgets) and artistic. Virtually, anything that needs to bend, can be, and is designed out of square and rectangular materials (HSS materials).

Notes

Square section steel often provides the ideal balance between strength, aesthetic appearance, and being functional.

These three reasons are why square metal tubing is still so popular to this day. But like the RHS sections, steel tube squares are difficult to use. It is hard to bolt them to beams. Square steel tubing also comes in ‘hot’ and ‘cold’ forms. Another name for them is a “box section”.

Photos of square pipe/TUBE bending machine

square pipe bending machine COST AND square tube bending machine PRICE

Our square pipe bending machine price is lower than our peers’, and our square tube bending machine is high quality, we have our own manufacturing factory, all products are factory price, there is absolutely no middleman markup, we accept both small section bender (Sectional modulus: 6 cm3 – 16 cm3 ) customer and large section bender (Sectional modulus: 1000 cm3) wholesale customer, section bending machines (also called profile roll bending machine) and angle bending machines for sale online.

5 minute reading

Induction bending of square tube

What is Induction Bending?

Induction Bending is a precisely controlled and efficient piping bending technique. Local heating using high frequency induced electrical power is applied during the induction bending process. Pipes, tubes, and even structural shapes (channels, W & H sections) can be bent efficiently in an induction bending machine. Induction bending is also known as hot bending, incremental bending, or high-frequency bending. For bigger pipe diameters, when cold bending methods are limited, Induction bending is the most preferable option. Around the pipe to be bent, an induction coil is placed that heats the pipe circumference in the range of 850 – 1100 degrees Celsius.

Induction Bending Process

The following steps are performed for induction bending of piping or pipeline system:

  • The pre-inspected pipe or pipeline to be bent is placed in the machine bed and clamped hydraulically.
  • Around the pipe, induction heating coils and cooling coils are mounted. To ensure uniform heating, the induction coil can be adjusted with a 3-plane movement.
  • By adjusting the radius arm and front clamp, the required bend radius can be fixed. There is one pointer to display a correct degree of turning.
  • Arc lengths are marked on the pipe. The pipe can be moved slowly whilst the bending force is applied by a fixed radius arm arrangement.
  • Once everything is set as required, hydraulic pressure, water level, and switches are inspected and then the induction bending operation is started.
  • Upon reaching the required temperature range, the pipe is pushed forward slowly at a speed of 10-40 mm/min, and the operation is stopped when the specified bend angle and pre-determined arc length is reached.
  • Just beyond the induction coil, the heated pipe material is quenched using a water spray on the outside surface of the pipe.
  • In the next step, the induction bend is removed and sent for inspection and measurement of tolerances.
  • The final step for the induction bends is the use of post bend heat treatments for stress relieving, normalizing, etc.

Induction bends are normally produced in standard bend angles (e.g. 45°, 90°, etc.). However, depending on the requirement they can be custom made to specific bend angles. Compound out-of-plane bends in a single joint of pipe can also be produced. The bend radius for induction bending is specified as a function of the nominal pipe diameter (D) like 5D, 30D, 60D bends, etc. Fig. 2 below provides a schematic diagram of the induction bending mechanism.

Seven important parameters that affect the induction bending square pipe process

  • Pipe Diameter
  • Surface Contamination
  • Process Parameters like Temperature, Speed, Cooling rate, etc
  • Bend Radius
  • Bend Angle
  • Process Interruptions
  • Hardenability of the Pipe Material, etc.

Induction Bending Standards

As the complex induction bending process involves various steps for producing bends, it must be controlled precisely to produce quality items. Different codes and standards govern this process. The most conventional and widely used standards for the induction bends are the ASME B16.49 and ISO 15590-1(en).

Advantages of Induction bending

The major advantages of induction bending are:

  • Lower risk of wall thinning and deformation of the cross-section
  • Thin-walled pipes can easily be bent.
  • Less costly and available faster than traditional components.
  • Uniform hardness and thickness.
  • Smooth flow due to large radii reducing friction, wear, and pump energy.
  • No pipe wrinkles.
  • Only a straight pipe is required for induction bending.
  • Precise bending radius and angle.
  • Diverse bendings: square pipe, flat bar, I-beam, H-beam, channel section, etc.

Applications of Induction bends

The majority of the Induction bends are found in the pipeline systems for liquid and gas transportation. Additionally, they are found in applications requiring large diameter bends with precision and reliability and where the laminar smooth flow is required. Typical applications of induction bends include the following industries:

  • Onshore and Offshore pipelines in the oil & gas sector
  • The refinery, chemical, and petrochemical sector
  • Powerplants
  • Industrial equipment
  • Infrastructure constructions and steel building constructions (a.o. bridges, construction, art objects, roller coasters)
  • Offshore energy (a.o. J-tubes, S-jubes)
  • Metallurgical industries
  • Shipbuilding, etc.

Induction Bending Materials

The following pipe materials are normally used for forming by induction bending:

  • Carbon steel
  • Stainless steel, Duplex Stainless Steel, Super Duplex Stainless Steel
  • Special steels, such as Inconel, S690QL, etc.
  • Aluminum, Titanium, Monel, Copper, Clad Pipe, etc.

:: Reference: Introduction to Induction Bending

PHB & MS Series Square Pipe/Tube Rolling Machine

BIT square pipe/tubing rolling machine can bend square pipe/tube into circle or arc.

square pipe rolling machine
  • Width (mm): 30-350
  • Height (mm): 20-350
  • Wall thickness (mm): 2-12

Note: A larger size square pipe/tubing roll bending machine can be customized

More detailed parameters

CNC Aluminum square tube/pipe bending machine

Can be bent in various shapes (3-D graphics, C-shaped, U-shaped, full circle, ellipse, multiple radii combination shapes, etc.). Suitable for bending of aluminum profiles for automobiles, doors and windows

square aluminum tube bending machine
  • Max . Section. Width (mm): 50-300
  • Max . Section. Height (mm): 70-500
  • Y-axis thrust (ton):10-70

More detailed parameters

ALUMINUM Square tubing/pipe BENDING MACHINE

Small aluminum profile bending machine with excellent performance, the main bending L-shaped, rectangular, U-shaped and other shapes.

aluminum c channel bending machine
  • Max. Section. Width (mm): 100
  • Max. Section. Height (mm): 200
  • Punching mechanism repeat positioning accuracy: < 0.01mm Spindle rated.
  • Spindle speed: 1-15r/min
  • Min bend radius: R=40mm

More detailed parameters

NC Square tube bending machine
square pipe bending machine
  • Width (mm): 18-168
  • Height (mm): 18-168
  • Wall thickness (mm): 2-14
  • Bending radius range (mm) :25-750
  • Maximum bending angle (°) :0-200
  • Core length (mm) :1800-5000

More detailed parameters